As the title say, basically Sasuke overused his MS so much he went blind, but the question is why? Sasuke had no intention of getting Itachi eyes so why overuse his eyes to get blind? Had Sasuke knew about Hashirama DNA preventing blindness would he have choice that instead of Itachi eyes?
Obito spammed Kamui yet no blindness while everyone who spammed MS went blind including Kakashi, who used Kamui way less than Obito.
Obito spammed Kamui yet no blindness while everyone who spammed MS went blind including Kakashi, who used Kamui way less than Obito.